Researchers from the University of Calgary in Alberta, Canada, compared the effectiveness of two different interventions for distressed survivors of breast cancer – group mindfulness meditation training with yoga vs. supportive-expressive group therapy.

This multisite, randomized controlled trial assigned 271 distressed survivors of stage I to III breast cancer to either a Mindfulness Based Cancer Recovery group (MBCR), a Supportive-Expressive Therapy Group (SET), or a 1-day stress management control condition.

MBCR focused on training in mindfulness meditation and gentle yoga, whereas SET focused on emotional expression and group support. Both intervention groups included 18 hours of professional contact.

Measures were collected at baseline and after the intervention by assessors who were blind to the study condition. Primary outcome measures were mood and diurnal salivary cortisol slopes. Secondary outcomes were stress symptoms, quality of life, and social support.

Using linear mixed-effects models, in intent-to-treat analyses, cortisol slopes were maintained over time in both SET (P = .002) and MBCR (P = .011) groups relative to the control group, whose cortisol slopes became flatter.

Women in MBCR improved more over time on stress symptoms compared with women in both the SET (P = .009) and control (P = .024) groups. Per-protocol analyses showed greater improvements in the MBCR group in quality of life compared with the control group (P = .005) and in social support compared with the SET group (P = .012).

This study, the largest trial to date, concludes that MBCR was superior for improving a range of psychological outcomes for distressed survivors of breast cancer. Both the SET and MBCR also resulted in more normative diurnal cortisol profiles than the control condition.